What's the real reason men take a long time to reply after first getting your number?

I met this guy at a club. We hit it off right away. He wasn't my normal type in looks, but we just really connected. He kind of acted like my boyfriend actually and my friend even said that. I was talking to him about the bartender and he got kind of jealous. But nothing like outrageous. Anyways, we exchanged numbers and sometimes he will text really slow. He kind of reminds me of my ex. My ex was more of the type to talk in person or on the phone instead of texting. But like one month into our relationship he opened up a little more, and would get annoyed if I had to go all of a sudden. Anyways Is it a technique for girls to want them more?